Local atomic 3D real space structural analysis of icosahedral Mg-Zn-RE (RE = Y and Ho) alloys: Strategy, method and models

Stefan Brühne (1) , Eckhard Uhrig (1) , Guido Kreiner (2) , Wolf Assmus (1)

1 Physikalisches Institut [Frankfurt/Main]
2 CPfS - Max-Planck-Institut für Chemische Physik fester Stoffe

The local structure of any condensed matter is accessible via an atomic pair distribution function (PDF) analysis. Here, the local atomic structure of the well-ordered quasicrystals fci-Mg25Y11Zn64, fci-Ho9Mg26Zn65 and si-Ho11Mg15Zn74 have been investigated by PDFs obtained from in-house X-ray and synchrotron powder data. Least-squares refinements using periodic 1/1- and 2/1-approximants as models for the local atomic structure have been performed. They reveal predominantly Frank-Kasper-type coordination polyhedra. The basic building block is a Bergman cluster of about 100 atoms with 14 Å diameter. RE8 cubes of edge length 5.4 Å are part of the cluster occupying pentagon dodecahedral positions. The cluster connection scheme follows in general that of Henley's Canonical Cell Tiling (CCT). However, according to our results, overlapping clusters are likely to be present in the quasicrystalline structure. Thus interpenetration seems to be a general feature for clusters in quasicrystals which complicates the ongoing discussion on their nature.

Mots clés: Physical Sciences

Stefan Brühne, Eckhard Uhrig, Guido Kreiner, Wolf Assmus. Local atomic 3D real space structural analysis of icosahedral Mg-Zn-RE (RE = Y and Ho) alloys: Strategy, method and models. Philosophical Magazine, 2005, 86 (03-05), pp.463-468. ⟨10.1080/14786430500333331⟩. ⟨hal-00513618⟩